可以在远程的链接上下载文件工具类

1.代码如下：

package com.jimulian.iwuxi.utils.datetools;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLDecoder;
import java.util.HashMap;
import java.util.Map;
public class GetFileByHttp {
    /**
     * description: 使用url 下载远程文件
     * @param urlPath  --- url资源
     * @param targetDirectory --- 目标文件夹
     * @throws Exception
     * @return void
     * @version v1.0
     * @author zhangcw
     * @date 2019年9月3日 下午8:29:01
     */
    public static void download(String urlPath , String targetDirectory) throws Exception {
        // 解决url中可能有中文情况
        System.out.println("url:"+ urlPath);
        URL url = new URL(urlPath);
        HttpURLConnection http = (HttpURLConnection)url.openConnection();
        http.setConnectTimeout(3000);
        // 设置 User-Agent 避免被拦截
        http.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)");
        String contentType = http.getContentType();
        System.out.println("contentType: "+ contentType);
        // 获取文件大小
        long length = http.getContentLengthLong();
        System.out.println("文件大小："+(length / 1024)+"KB");
        // 获取文件名
        String fileName = getFileName(http , urlPath);
        InputStream inputStream = http.getInputStream();
        byte[] buff = new byte[1024*10];
        OutputStream out = new FileOutputStream(new File(targetDirectory,fileName));
        int len ;
        int count = 0; // 计数
        while((len = inputStream.read(buff)) != -1) {
            out.write(buff, 0, len);
            out.flush();
            ++count ;
        }
        System.out.println("count:"+ count);
        // 关闭资源
        out.close();
        inputStream.close();
        http.disconnect();
    }

    /**
     * description: 获取文件名
     * @param http
     * @param urlPath
     * @throws UnsupportedEncodingException
     * @return String
     * @version v1.0
     * @author w
     * @date 2019年9月3日 下午8:25:55
     */
    private static String getFileName(HttpURLConnection http , String urlPath) throws UnsupportedEncodingException {
        String headerField = http.getHeaderField("Content-Disposition");
        String fileName = null ;
        if(null != headerField) {
            String decode = URLDecoder.decode(headerField, "UTF-8");
            fileName = decode.split(";")[1].split("=")[1].replaceAll("\"", "");
            System.out.println("文件名是： "+ fileName);
        }
        if(null == fileName) {
            // 尝试从url中获取文件名
            String[] arr  = urlPath.split("/");
            fileName = arr[arr.length - 1];
            System.out.println("url中获取文件名："+ fileName);
        }
        return fileName;
    }

    public static void main(String[] args) {
        Map<String,String> map = new HashMap<>();
        map.put("下载图片", "https://wx.qlogo.cn/mmopen/vi_32/1GF7icxunI3bxh98iaQxHlUmeBwP3tZy7XpGufb8AKaKtic250Gic1qQFBuXDpFM1fjIVDd6gzyZ9oINbRmGribC7iag/132");
//        map.put("下载图片", "http://i1.zhiaigou.com/uploads/tu/201908/9999/152a0cd3b5.jpg");
//        map.put("下载中文图片", "http://47.93.217.218/chapter/downloadServlet?fileName=%E4%B8%AD%E6%96%87%E5%9B%BE%E7%89%87.jpg");
//        map.put("下载QQ软件", "https://qd.myapp.com/myapp/qqteam/pcqq/PCQQ2019.exe");
//        map.put("下载带中文文件", "http://32204.xc.mieseng.com/xiaz/%E8%BF%85%E9%9B%B7%E5%A4%8D%E6%B4%BB%E7%89%88@68_416334.exe");
//        map.put("该资源无法下载", "https://www.csc108.com/announcementNotice/showFile.json?id=685");
        try {
            for(String urlStr : map.values()) {
                download(urlStr, "D:/");
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        System.out.println("process over ...");
    }
}

2.运行main方法如下：